Classifications

• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06P—DYEING OR PRINTING TEXTILES; DYEING LEATHER, FURS OR SOLID MACROMOLECULAR SUBSTANCES IN ANY FORM
  • D06P5/00—Other features in dyeing or printing textiles, or dyeing leather, furs, or solid macromolecular substances in any form
  • D06P5/15—Locally discharging the dyes
  • D06P5/153—Locally discharging the dyes with oxidants
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06P—DYEING OR PRINTING TEXTILES; DYEING LEATHER, FURS OR SOLID MACROMOLECULAR SUBSTANCES IN ANY FORM
  • D06P5/00—Other features in dyeing or printing textiles, or dyeing leather, furs, or solid macromolecular substances in any form
  • D06P5/15—Locally discharging the dyes

Definitions

• 4,218,220 discloses that it is sometimes desir ⁇ able to prepare prefaded denim garments uniformly faded, that is prefaded blue jeans free of unwanted streaks. Satisfactory, unstreaked, suitably faded blue jeans were hitherto obtained only by repeated washings.
• the patent teaches subjecting the denim fabric to a washing cycle comprising an initial wash with detergent and e ulsifier, a suitable interme ⁇ diate rinsing operation, a bleaching operation in which the garments are subjected to the simultaneous action of bleach and a fabric softener of the quater ⁇ nary ammonium type, alone or with the addition of a suitable amount of detergent, a further rinsing operation, and an optional final treatment with fabric softener and laundry sour.
• a chlorine bleach such as, sodium hypo- chlorite or trichloroisocyanuric acid or the like as a bleach.
• 4,852,990 teaches a modi ⁇ fication wherein denim garments first are desized, then contacted with an aqueous polyacrylic acid solu ⁇ tion. A chlorine-type bleaching agent is subsequent ⁇ ly added to provide a uniform bleached appearance. Subsequently, the trend has been toward a look featuring random faded effects.
• U.S. Patent No. 4,740,213 discloses a process in which granules of a coarse, permeable material, such as pumice, are impregnated with a chlorine bleaching agent tumbled in a drum with denim fabric in a dry state. Subsequent traces of the chlorine bleaching agent are removed, optionally by an antichlor such as acidic hydrogen peroxide.
• an antichlor such as acidic hydrogen peroxide.
• chlorine bleaching agents are known to be very destructive to cotton, consequently alterna ⁇ tive bleaching agents have been employed to produce the faded look. Potassium permanganate is very de ⁇ sirable for such an oxidative treatment.
• the present invention is a process for wet pro- cessing denim fabric containing dyestuff colorbodies by desizing the denim fabric, washing the desized fabric, contacting the washed fabric with potassium permanganate to oxidize part of the colorbodies in the denim fabric to a form which is easily removed from the fabric surface, thereby decolorizing the denim fabric, and neutralizing the decolorized denim fabric by removing residues of the potassium per ⁇ manganate and of the oxidized colorbodies, the improvement comprising the steps of (a) neutralizing the oxidized denim fabric by (i) immersing the denim fabric in about 5 to 20 parts by weight of a first aqueous solution per part by weight denim fabric, (ii) maintaining said first aqueous solution between pH 3.0 and 6.0, (iii) subsequently incorporating about 2 parts by weight of either a monodentate or multidentate carboxylic acid chelating agent or salt or combination thereof, and 1 part by weight hydrogen peroxide, and (iv)
• Unless otherwise specified percent or parts by weight is on the basis of 100% of undiluted compound by weight.
• 1 part by weight hydrogen peroxide requires 2 parts by weight of an aqueous solution of 50% H 2 0 2 •
• 3 parts by weight 35% H 0 2 is equivalent to about 1 part by weight hydrogen peroxide on a 100% basis.
• the denim fabric may be treated in any convenient form such as uncut piece goods, as partially fabri ⁇ cated garments or as finished garments.
• Denim is conventionally woven with colored warp and white filling threads but would include striped denim fabrics or denim fabrics woven with both warp and filling threads colored.
• the denims are dyed with vat dyes such as indigo or sulfur dies or the like.
• Denim fabrics may also be woven with mixtures of cotton and' synthetic fibers.
• the process is particularly useful for producing a denim with a random faded pattern by the process of desizing the denim fabric, washing the desized fabric, contacting the washed fabric with potassium permanganate to oxidize part of the colorbodies in the denim fabric to a form which is easily removed from the fabric surface, thereby decolorizing the denim fabric, and neutralizing the decolorized denim fabric by removing residues of the potassium per- manganate and of the oxidized colorbodies, the improvement comprising the steps of (a) neutralizing the oxidized denim fabric by (i) immersing the denim fabric in about 5 to 20 parts by weight of a first aqueous solution per part by weight denim fabric, ( ⁇ ) maintaining said first aqueous solution between pH 3.0 and 6.0, (iii) subsequently incorporating about 2 parts by weight of either a monodentate or multidentate carboxylic acid chelating agent or salt or combination thereof, and 1 part by weight hydrogen peroxide, and (iv) maintaining said first aqueous
• the denim fabric may be desized by contacting the denim fabric with an effective amount of a peroxygen compound and 0.2% to 3% surfactant (preferably 1% to 2%) at pH 7-12 (preferably 9-10) for a sufficient time (5-15 minutes, preferably 10-12 minutes) , thereby substantially removing sizing therefrom.
• An effective amount of a peroxygen com ⁇ pound for desizing is desirably 0.5% to 3% sodium persulfate or 2% to 6% hydrogen peroxide (100% basis) . This process overcomes the environmentally- undesirable effluents from current desizing processes employing enzymes or sodium perborate.
• Either sodium persulfate or hydrogen peroxide are particularly desirable to remove both starch and polyvinyl alcohol, the two types of sizing generally used for weaving denims.
• EXAMPLES Desizing Add the inverted garments to a large washer. Fill the washer with enough hot water (65°-90°C; 150°-190°F) to produce a goods to liquor ratio of 1:20 or less. Add 2%-6% on the weight of the goods (owg) 35% H 2 0 2 (3%-4% owg optimum) . Add a wetting agent or surfactant 0.2%-3% owg (l%-2% optimum) and enough alkali to reach a pH of 7-12 (9-10 optimum) . React 8-15 minutes (10-12 optimum) . Rinse with hot water (65°-90°C; 150°-190°F) agitating 4-10 minutes. Repeat rinse as necessary to prevent the redeposition of size.
• Sodium persulfate 0.5%-3% owg (l%-2% owg optimum) can be substituted for H 0 2 in desizing.
• Optimum temperature is 80°-85°C (175°-185°F) .
• H 2°2. H 2 0 2 35% should be in the range of 2%-5% owg (3%-4% optimum) .
• the pH of this system is approxi ⁇ mately 4, considerably higher than the pH of 2.5-3 obtained when using sulfite or hydroxylamine systems.
• the chelating agents may be any multidentate carboxylic acid based agent, particularly those show ⁇ ing affinity for manganese or promoting the reduction of manganese (VIIj V or IV) to manganese II, for example, EDTA (ethylenediamine tetraacetic acid) , DTPA (diethylenetriamine pentaacetic acid) .
• a com ⁇ flashal product such as Dow Chemical Corporation's Versenex 80TM which contains >38% pentasodium DTPA and other noninert compounds is particularly convenient.
• the garments are treated with an alkaline formulation of H 2 0 2 as a replacement for hypochlorite or per ⁇ borate. This step bleaches the decolorized portions of the garment enhancing the contrast between dyed and decolorized areas.
• EXAMPLE 1 Desizing of Garments-Production Facility
• One hundred twenty pair (about 100 kg) of blue denim jeans were inverted and added to a 200 kg capa ⁇ city washer.
• the washer was filled to high level with hot water (75°C) to maintain a goods to liquor weight ratio of 1:20 or less.
• About 1.8 kg, 35% H 2 ° 2 ' 85 9 nonionic liquid detergent and enough caustic or soda ash to reach a pH of 9 were added; "the garments were agitated 7 minutes and drained.
• the washer was then filled to high level with hot water (75°C) ; agitated 4 minutes and drained. Washer was filled again to high level with warm water (45°C) ; agitated 4 minutes, drained and extracted.
• EXAMPLE 2 Decolorization of Garments-Production Facility Desized garments were righted and 60 garments (about 50 kg) were added to a tumbler containing 100- 150 kg KMn ⁇ 4 soaked pumice stones. Stones and gar ⁇ ments were tumbled (rocked) together for 20 minutes. EXAMPLE 3
• Garments decolorized in Example 2 appeared brown and gritty. Removal of the brown stain was necessary to obtain the desired appearance.
• One hundred twenty (about 100 kg) "rocked" jeans were added to a 200 kg capacity washer. Washer was filled to high level with hot water 175°C; 110 g neutral liquid detergent was added, the garments were agitated 4 minutes and drained. The washer was filled to low level with hot water (75°C) to maintain a goods to liquor ratio of 1:20 or less. Added in this order were 1.6 kg glacial acetic acid and 1.6 kg of Versenex 80TM chelating agent (Dow Chemical). Then 2.45 kg of 35% H 0 2 was added. The garments were agitated 7 minutes and drained.
• the washer was filled again to high level with hot water (75°C) ; 110 g neutral liquid detergent was added; the garments were agitated 2 minutes and drained. Then the washer was filled to low level with hot water; 1.6 kg glacial acetic acid, 1.6 kg chelating agent and 2.45 kg 35% H 2 0 2 were added. The garments were agitated 7 minutes, drained and extracted. The washer was filled to high level with hot water (75°C) , agitated 2 minutes and drain ⁇ ed. The rinse was repeated. The washer was then filled to high level with hot water (75°C) ; 3.6 kg 35% H 2 0 2 and enough alkali to reach a pH of 9 were added. Garments were agitated 4 minutes and drained.
• Neutrali ⁇ zation liquor was prepared by adding 3% owg 35% H 2 0 2 , 2% owg acetic acid and 2% owg chelating agent to deionized water and bringing-the volume to 100 mL.
• Chelating agent used was Versenex 80TM. Other poly- dentate chelating agents may be used and mention of this product is not to limit the scope of this inven ⁇ tion.
• Sample and the liquor were agitated for 10 minutes at 65°C in an oscillating bath. The liquor was dropped and the neutralization step repeated. After the second neutralization, the liquor was drained and the sample was brightened by adding 100 mL of a 2% owg H 2 0 solution adjusted to pH 9 with NaOH.
• Sample and liquor were agitated for 10 minutes at 65°C in an oscillating bath. Following brighten- ing, the sample was rinsed twice with 100 mL portions of deionized water for 2 minutes in the oscillating bath at 65°C. Samples were air dried.

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Detergent Compositions (AREA)
• Coloring (AREA)

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Citations (2)

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• 1989
  • 1989-12-15 US US07/451,067 patent/US5006124A/en not_active Expired - Fee Related
• 1990
  • 1990-12-03 AU AU70332/91A patent/AU7033291A/en not_active Abandoned
  • 1990-12-03 JP JP3501949A patent/JPH0723579B2/ja not_active Expired - Lifetime
  • 1990-12-03 KR KR1019920701401A patent/KR940007704B1/ko not_active IP Right Cessation
  • 1990-12-03 WO PCT/US1990/007060 patent/WO1991009171A1/en unknown

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